Process of purifying waste mercerization-lyes.



UNITED STATES PATENT OFFICE.

PAUL KRAIS, OF TU'BINGEN-LUSTNAU, GERMANY, ASSIGNOR T0 MAX PETZOLD, OF.

ZITTAU, GERMANY.

PROCESS OF PURIFYIN G WASTE MERCERIZATION-LYES.

No Drawing.

7 '0 all whom it may concern lie it known that 1, PAUL Knxis, a subjcct of the German Emperor, and residing at 'liibingen-Lustnau, Germany, have invented a certain new and useful Improved Process of Purifying .W'aste Mercerizatioir Lyes, of which the following is a specification.

The subject-matter of my present invention is a modification of the process for purifying the soda-lye rendered impure by the mercerization process according to the Letters Patent 967272, Otto enter, of Aug. 9, 1910.

According to my invention the waste lye containing size is now treated with a mixture of lime and clay, and an agent for effecting flocculence may be added to the i'eactionmass.

The new purifying process can be carried out without the addition of soda.

This process is an improvei'ncut of the method described in the said patent inasmuch as, firstly, a smaller quantity of insoluble substances to be added to the sodalye so that accordingly a smaller reactionmass is to be used up, and secondly, it does not depend on an addition of soda, so that when the conditions of the mercerization process necessitate this, only so much waste lye or caustic soda is purified as has been recovered from the mercerized goods. On the other hand, however, without impairing the process so much soda and quick lime can be added, or separately boiled to form sodalye or, finally, so much solid or dissolved caustic soda can be added as is required as a substitute for the lost caustic soda or for the lye used up for other purposes.

My new process is based on the observation that by adding clay to the reactionmass a mechanical or mechanical-chemical combination of the clay with the size con- ,tained in the waste lye is presumably formed. The quantity of lime necessary for remciving the size can be reduced to a considerable extent. Preferably clay dried in the air is employed in the form of powder, which is as little soluble as possible in sodalye. By means of this addition of clay it is, for example, possible successfully to remove the size to such an extent from waste lye, which required ,for 5000 liters (320 kilos quick-lime and 150 kilos soda (when consequently if 120 kilos quick-lime be reckoned Patented Aug. 20, 19,12.

for the caustification of the soda 500 kilos quick-lune was necessary for the removal of the size) by an addition of 125 kilos clay and 125 kilos quick-lime, that the purified lye can be boiled down and gives the full lnercerization elfect 011 being used a ain. Consequently instead of 500 only 250 zilos solid matter is added. The added clay acts, however, at a temperature far below the boiling point. In many instances the puri-' tying operation can be satisfactorily performed even at the temperature at which the waste 'lye comes from the mercerizing machine, that is at say 30 to 50 Celsius, so

that a further saving in time and expense is effected.

In practice it has proved advisable to add to the lye to be regenerated a small quantity of an agent for producing flocculence, the extremely fine precipitate which is often difficult to filter assuming a flocculent form, becoming entirely deposited and being much more easy to filter. A soluble lead salt, for

example, sugar of lead, is referably employed as such an agent, said sugar of lead dissolved in water being stirred into the mixture, whereupon a kind of coagulation of the sediment immediately occurs. 'Whereas, however, it is necessary to be extremely careful with this admixture when lime alone v(or lime and soda) is used, because otherwise lead, probably as sodium plumbate,

goes into solution and passes also into the mercerization process, whereby during the subsequent dyein operation disturbances readily occur, it is possible in the case of the new process to use the sugar of lead admixture without injury up to 2 to 2.5 kilos per 5000 liters waste lye, a quantity which corresponds with the maximum flocculence efi'ect.

It may be mentioned by way of example that to 5000 kg. of waste-lye of 10 Baum containing size, dextrin and other impuri ties, 125 kg. of pulverized clay dried in the air and 125 kg. of caustic lime are added, whereafter the whole is durin one hour heated in stirring up to 50 Celsius, 2 kg. of sugar of lead dissolved in 10 kg. hot water are then added. The size and the impurities of'the water-lye form with the clay and the caustic lime a mechanical-chemical com,- position, which by the addition of sugar of lead is precipitated in a flocculent form which is to be removed by filtration.

I claim y I 1. The process of purifying Waste-meroeri- Zation-lye consisting in heating the lye, in adding thereto-a quantity of lime and pulverized clay whereby a sediment is obtained and in removing the sediment.

2. The process of purifying Waste-meroerization-lye consisting in heating the lye, in adding thereto a quantity of lime and pulverized clay, in mixing an agent for producing fiocculence therewith whereby a flooeulent sediment is obtained and in removing the sediment.

3. The process of purifying Waste-mercerization-lye consisting in heating the soda-lye, 15 in adding a mixture of lime and clay to the soda-lye, in mixing sugar of lead therewith, whereby a fiocculent sediment is obtained and in removing the sediment by filtration.

In testimony whereof, Iafiix my signature 20 in the presence of two Witnesses.

PAUL KBAIS.

Witnesses PAULINE KLAIBER, ERNEST ENTENMANN. 

